looking for example of Drupal site with templated subsites

I'm looking for any Production examples of Drupal being used on a site to host multiple user-generated sub sites. Imagine you want to create a site for running clubs. You have a main site where any running club can create their own subsite. So you have running.com/site/portland, running.com/site/denver, running.com/site/atlanta, etc. Each sub site is maintained by an admin of that group. Each subsite controls its own content and user access. New subsites can be spun up quickly from the same template look and feel.

If you have ever seen caringbridge.org, that is what I'm looking for.
Is organic groups sufficient for this purpose? Can someone send me examples of sites set up this way?
Thanks in advance,
John